/*
 * @BEGIN LICENSE
 *
 * Psi4: an open-source quantum chemistry software package
 *
 * Copyright (c) 2007-2024 The Psi4 Developers.
 *
 * The copyrights for code used from other parties are included in
 * the corresponding files.
 *
 * This file is part of Psi4.
 *
 * Psi4 is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * Psi4 is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with Psi4; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * @END LICENSE
 */

/*! \file
    \ingroup CCLAMBDA
    \brief Enter brief description of file here
*/

/*! \defgroup CCLAMBDA cclambda: Coupled-Cluster Lambda Equations */

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include "psi4/libciomr/libciomr.h"
#include "psi4/libpsio/psio.h"
#include "psi4/libiwl/iwl.h"
#include "psi4/libdpd/dpd.h"
#include "psi4/libqt/qt.h"
#include "psi4/psifiles.h"
#include "MOInfo.h"
#include "Params.h"
#define EXTERN
#include "globals.h"

namespace psi {
namespace cclambda {

void halftrans(dpdbuf4 *Buf1, int dpdnum1, dpdbuf4 *Buf2, int dpdnum2, double ***C, int nirreps, int **mo_row,
               int **so_row, int *mospi, int *sospi, int type, double alpha, double beta);

void AO_contribute(int p, int q, int r, int s, double value, dpdbuf4 *tau1_AO, dpdbuf4 *tau2_AO, int anti);

void BL2_AO(int L_irr) {
    int h, nirreps, i, Gc, Gd, Ga, Gb, ij;
    double ***C, **X;
    int *orbspi, *virtpi;
    int **T2_cd_row_start, **T2_pq_row_start, offset, cd, pq;
    dpdbuf4 tau, t2, tau1_AO, tau2_AO;
    psio_address next;
    struct iwlbuf InBuf;
    int idx, p, q, r, s, filenum;
    int lastbuf;
    double value, tolerance = 1e-14;
    Value *valptr;
    Label *lblptr;

    nirreps = moinfo.nirreps;
    orbspi = moinfo.orbspi;
    virtpi = moinfo.virtpi;
    C = moinfo.C;

    T2_cd_row_start = init_int_matrix(nirreps, nirreps);
    for (h = 0; h < nirreps; h++) {
        for (Gc = 0, offset = 0; Gc < nirreps; Gc++) {
            Gd = Gc ^ h;
            T2_cd_row_start[h][Gc] = offset;
            offset += virtpi[Gc] * virtpi[Gd];
        }
    }

    T2_pq_row_start = init_int_matrix(nirreps, nirreps);
    for (h = 0; h < nirreps; h++) {
        for (Gc = 0, offset = 0; Gc < nirreps; Gc++) {
            Gd = Gc ^ h;
            T2_pq_row_start[h][Gc] = offset;
            offset += orbspi[Gc] * orbspi[Gd];
        }
    }

    /************************************* AA *****************************************/

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIJPQ (1)");
    global_dpd_->buf4_scm(&tau1_AO, 0.0);

    dpd_set_default(0);
    global_dpd_->buf4_init(&tau, PSIF_CC_LAMBDA, L_irr, 0, 5, 2, 7, 0, "LIJAB");

    halftrans(&tau, 0, &tau1_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 0, 1.0, 0.0);

    global_dpd_->buf4_close(&tau);
    global_dpd_->buf4_close(&tau1_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIJPQ (1)");
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIJPQ (2)");
    global_dpd_->buf4_scm(&tau2_AO, 0.0);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_init(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_rd(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_init(&tau2_AO, h);
    }

    iwl_buf_init(&InBuf, PSIF_SO_TEI, tolerance, 1, 1);

    lblptr = InBuf.labels;
    valptr = InBuf.values;
    lastbuf = InBuf.lastbuf;

    for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
        p = std::abs((int)lblptr[idx++]);
        q = (int)lblptr[idx++];
        r = (int)lblptr[idx++];
        s = (int)lblptr[idx++];

        value = (double)valptr[InBuf.idx];

        /*    outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

        AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 1);
    }
    while (!lastbuf) {
        iwl_buf_fetch(&InBuf);
        lastbuf = InBuf.lastbuf;
        for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
            p = std::abs((int)lblptr[idx++]);
            q = (int)lblptr[idx++];
            r = (int)lblptr[idx++];
            s = (int)lblptr[idx++];

            value = (double)valptr[InBuf.idx];

            /*      outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

            AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 1);
        }
    }

    iwl_buf_close(&InBuf, 1);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_wrt(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau1_AO, h);
    }
    global_dpd_->buf4_close(&tau1_AO);
    global_dpd_->buf4_close(&tau2_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIJPQ (2)");

    dpd_set_default(0);
    global_dpd_->buf4_init(&t2, PSIF_CC_LAMBDA, L_irr, 0, 5, 2, 7, 0, "New LIJAB");

    halftrans(&t2, 0, &tau2_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 1, 0.5, 1.0);

    global_dpd_->buf4_close(&t2);
    global_dpd_->buf4_close(&tau2_AO);

    /************************************* BB *****************************************/

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "Lijpq (1)");
    global_dpd_->buf4_scm(&tau1_AO, 0.0);

    dpd_set_default(0);
    global_dpd_->buf4_init(&tau, PSIF_CC_LAMBDA, L_irr, 0, 5, 2, 7, 0, "Lijab");

    halftrans(&tau, 0, &tau1_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 0, 1.0, 0.0);

    global_dpd_->buf4_close(&tau);
    global_dpd_->buf4_close(&tau1_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "Lijpq (1)");
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "Lijpq (2)");
    global_dpd_->buf4_scm(&tau2_AO, 0.0);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_init(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_rd(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_init(&tau2_AO, h);
    }

    iwl_buf_init(&InBuf, PSIF_SO_TEI, tolerance, 1, 1);

    lblptr = InBuf.labels;
    valptr = InBuf.values;
    lastbuf = InBuf.lastbuf;

    for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
        p = std::abs((int)lblptr[idx++]);
        q = (int)lblptr[idx++];
        r = (int)lblptr[idx++];
        s = (int)lblptr[idx++];

        value = (double)valptr[InBuf.idx];

        /*    outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

        AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 1);
    }
    while (!lastbuf) {
        iwl_buf_fetch(&InBuf);
        lastbuf = InBuf.lastbuf;
        for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
            p = std::abs((int)lblptr[idx++]);
            q = (int)lblptr[idx++];
            r = (int)lblptr[idx++];
            s = (int)lblptr[idx++];

            value = (double)valptr[InBuf.idx];

            /*      outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

            AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 1);
        }
    }

    iwl_buf_close(&InBuf, 1);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_wrt(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau1_AO, h);
    }
    global_dpd_->buf4_close(&tau1_AO);
    global_dpd_->buf4_close(&tau2_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "Lijpq (2)");

    dpd_set_default(0);
    global_dpd_->buf4_init(&t2, PSIF_CC_LAMBDA, L_irr, 0, 5, 2, 7, 0, "New Lijab");

    halftrans(&t2, 0, &tau2_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 1, 0.5, 1.0);

    global_dpd_->buf4_close(&t2);
    global_dpd_->buf4_close(&tau2_AO);

    /************************************* AB *****************************************/

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIjPq (1)");
    global_dpd_->buf4_scm(&tau1_AO, 0.0);

    dpd_set_default(0);
    global_dpd_->buf4_init(&tau, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIjAb");

    halftrans(&tau, 0, &tau1_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 0, 1.0, 0.0);

    global_dpd_->buf4_close(&tau);
    global_dpd_->buf4_close(&tau1_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau1_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIjPq (1)");
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIjPq (2)");
    global_dpd_->buf4_scm(&tau2_AO, 0.0);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_init(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_rd(&tau1_AO, h);
        global_dpd_->buf4_mat_irrep_init(&tau2_AO, h);
    }

    iwl_buf_init(&InBuf, PSIF_SO_TEI, tolerance, 1, 1);

    lblptr = InBuf.labels;
    valptr = InBuf.values;
    lastbuf = InBuf.lastbuf;

    for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
        p = std::abs((int)lblptr[idx++]);
        q = (int)lblptr[idx++];
        r = (int)lblptr[idx++];
        s = (int)lblptr[idx++];

        value = (double)valptr[InBuf.idx];

        /*    outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

        AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 0);
    }
    while (!lastbuf) {
        iwl_buf_fetch(&InBuf);
        lastbuf = InBuf.lastbuf;
        for (idx = 4 * InBuf.idx; InBuf.idx < InBuf.inbuf; InBuf.idx++) {
            p = std::abs((int)lblptr[idx++]);
            q = (int)lblptr[idx++];
            r = (int)lblptr[idx++];
            s = (int)lblptr[idx++];

            value = (double)valptr[InBuf.idx];

            /*      outfile->Printf( "<%d %d %d %d = %20.10lf\n", p, q, r, s, value); */

            AO_contribute(p, q, r, s, value, &tau1_AO, &tau2_AO, 0);
        }
    }

    iwl_buf_close(&InBuf, 1);

    for (h = 0; h < nirreps; h++) {
        global_dpd_->buf4_mat_irrep_wrt(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau2_AO, h);
        global_dpd_->buf4_mat_irrep_close(&tau1_AO, h);
    }
    global_dpd_->buf4_close(&tau1_AO);
    global_dpd_->buf4_close(&tau2_AO);

    dpd_set_default(1);
    global_dpd_->buf4_init(&tau2_AO, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "LIjPq (2)");

    dpd_set_default(0);
    global_dpd_->buf4_init(&t2, PSIF_CC_LAMBDA, L_irr, 0, 5, 0, 5, 0, "New LIjAb");

    halftrans(&t2, 0, &tau2_AO, 1, C, nirreps, T2_cd_row_start, T2_pq_row_start, virtpi, orbspi, 1, 1.0, 1.0);

    global_dpd_->buf4_close(&t2);
    global_dpd_->buf4_close(&tau2_AO);

    free(T2_cd_row_start);
    free(T2_pq_row_start);

    /* Reset the default dpd back to 0 --- this stuff gets really ugly */
    dpd_set_default(0);
}

void AO_contribute(int p, int q, int r, int s, double value, dpdbuf4 *tau1_AO, dpdbuf4 *tau2_AO, int anti) {
    int Gp, Gq, Gr, Gs, Gpr, Gps, Gqr, Gqs, Grp, Gsp, Grq, Gsq;
    int pr, ps, qr, qs, rp, rq, sp, sq, pq, rs;
    int row;

    Gp = tau1_AO->params->rsym[p];
    Gq = tau1_AO->params->rsym[q];
    Gr = tau1_AO->params->rsym[r];
    Gs = tau1_AO->params->rsym[s];

    pq = tau1_AO->params->colidx[p][q];
    rs = tau1_AO->params->colidx[r][s];

    if (p != q && r != s) {
        /* (pq|rs) */
        Gpr = Gp ^ Gr;
        pr = tau1_AO->params->colidx[p][r];
        qs = tau1_AO->params->colidx[q][s];
        sq = tau1_AO->params->colidx[s][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gpr]; row++) {
            tau2_AO->matrix[Gpr][row][pr] += value * tau1_AO->matrix[Gpr][row][qs];
            if (anti) tau2_AO->matrix[Gpr][row][pr] -= value * tau1_AO->matrix[Gpr][row][sq];
        }

        /* (pq|sr) */
        Gps = Gp ^ Gs;
        ps = tau1_AO->params->colidx[p][s];
        qr = tau1_AO->params->colidx[q][r];
        rq = tau1_AO->params->colidx[r][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gps]; row++) {
            tau2_AO->matrix[Gps][row][ps] += value * tau1_AO->matrix[Gps][row][qr];
            if (anti) tau2_AO->matrix[Gps][row][ps] -= value * tau1_AO->matrix[Gps][row][rq];
        }

        /* (qp|rs) */
        Gqr = Gq ^ Gr;
        qr = tau1_AO->params->colidx[q][r];
        ps = tau1_AO->params->colidx[p][s];
        sp = tau1_AO->params->colidx[s][p];

        for (row = 0; row < tau1_AO->params->rowtot[Gqr]; row++) {
            tau2_AO->matrix[Gqr][row][qr] += value * tau1_AO->matrix[Gqr][row][ps];
            if (anti) tau2_AO->matrix[Gqr][row][qr] -= value * tau1_AO->matrix[Gqr][row][sp];
        }

        /* (qp|sr) */
        Gqs = Gq ^ Gs;
        qs = tau1_AO->params->colidx[q][s];
        pr = tau1_AO->params->colidx[p][r];
        rp = tau1_AO->params->colidx[r][p];

        for (row = 0; row < tau1_AO->params->rowtot[Gqs]; row++) {
            tau2_AO->matrix[Gqs][row][qs] += value * tau1_AO->matrix[Gqs][row][pr];
            if (anti) tau2_AO->matrix[Gqs][row][qs] -= value * tau1_AO->matrix[Gqs][row][rp];
        }

        if (pq != rs) {
            /* (rs|pq) */
            Grp = Gp ^ Gr;
            rp = tau1_AO->params->colidx[r][p];
            sq = tau1_AO->params->colidx[s][q];
            qs = tau1_AO->params->colidx[q][s];

            for (row = 0; row < tau1_AO->params->rowtot[Grp]; row++) {
                tau2_AO->matrix[Grp][row][rp] += value * tau1_AO->matrix[Grp][row][sq];
                if (anti) tau2_AO->matrix[Grp][row][rp] -= value * tau1_AO->matrix[Grp][row][qs];
            }

            /* (sr|pq) */
            Gsp = Gp ^ Gs;
            sp = tau1_AO->params->colidx[s][p];
            qr = tau1_AO->params->colidx[q][r];
            rq = tau1_AO->params->colidx[r][q];

            for (row = 0; row < tau1_AO->params->rowtot[Gsp]; row++) {
                tau2_AO->matrix[Gsp][row][sp] += value * tau1_AO->matrix[Gsp][row][rq];
                if (anti) tau2_AO->matrix[Gsp][row][sp] -= value * tau1_AO->matrix[Gsp][row][qr];
            }

            /* (rs|qp) */
            Grq = Gq ^ Gr;
            rq = tau1_AO->params->colidx[r][q];
            ps = tau1_AO->params->colidx[p][s];
            sp = tau1_AO->params->colidx[s][p];

            for (row = 0; row < tau1_AO->params->rowtot[Grq]; row++) {
                tau2_AO->matrix[Grq][row][rq] += value * tau1_AO->matrix[Grq][row][sp];
                if (anti) tau2_AO->matrix[Grq][row][rq] -= value * tau1_AO->matrix[Grq][row][ps];
            }

            /* (sr|qp) */
            Gsq = Gq ^ Gs;
            sq = tau1_AO->params->colidx[s][q];
            pr = tau1_AO->params->colidx[p][r];
            rp = tau1_AO->params->colidx[r][p];

            for (row = 0; row < tau1_AO->params->rowtot[Gsq]; row++) {
                tau2_AO->matrix[Gsq][row][sq] += value * tau1_AO->matrix[Gsq][row][rp];
                if (anti) tau2_AO->matrix[Gsq][row][sq] -= value * tau1_AO->matrix[Gsq][row][pr];
            }
        }

    } else if (p != q && r == s) {
        /* (pq|rs) */
        Gpr = Gp ^ Gr;
        pr = tau1_AO->params->colidx[p][r];
        qs = tau1_AO->params->colidx[q][s];
        sq = tau1_AO->params->colidx[s][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gpr]; row++) {
            tau2_AO->matrix[Gpr][row][pr] += value * tau1_AO->matrix[Gpr][row][qs];
            if (anti) tau2_AO->matrix[Gpr][row][pr] -= value * tau1_AO->matrix[Gpr][row][sq];
        }

        /* (qp|rs) */
        Gqr = Gq ^ Gr;
        qr = tau1_AO->params->colidx[q][r];
        ps = tau1_AO->params->colidx[p][s];
        sp = tau1_AO->params->colidx[s][p];

        for (row = 0; row < tau1_AO->params->rowtot[Gqr]; row++) {
            tau2_AO->matrix[Gqr][row][qr] += value * tau1_AO->matrix[Gqr][row][ps];
            if (anti) tau2_AO->matrix[Gqr][row][qr] -= value * tau1_AO->matrix[Gqr][row][sp];
        }

        if (pq != rs) {
            /* (rs|pq) */
            Grp = Gp ^ Gr;
            rp = tau1_AO->params->colidx[r][p];
            sq = tau1_AO->params->colidx[s][q];
            qs = tau1_AO->params->colidx[q][s];

            for (row = 0; row < tau1_AO->params->rowtot[Grp]; row++) {
                tau2_AO->matrix[Grp][row][rp] += value * tau1_AO->matrix[Grp][row][sq];
                if (anti) tau2_AO->matrix[Grp][row][rp] -= value * tau1_AO->matrix[Grp][row][qs];
            }

            /* (rs|qp) */
            Grq = Gq ^ Gr;
            rq = tau1_AO->params->colidx[r][q];
            ps = tau1_AO->params->colidx[p][s];
            sp = tau1_AO->params->colidx[s][p];

            for (row = 0; row < tau1_AO->params->rowtot[Grq]; row++) {
                tau2_AO->matrix[Grq][row][rq] += value * tau1_AO->matrix[Grq][row][sp];
                if (anti) tau2_AO->matrix[Grq][row][rq] -= value * tau1_AO->matrix[Grq][row][ps];
            }
        }

    }

    else if (p == q && r != s) {
        /* (pq|rs) */
        Gpr = Gp ^ Gr;
        pr = tau1_AO->params->colidx[p][r];
        qs = tau1_AO->params->colidx[q][s];
        sq = tau1_AO->params->colidx[s][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gpr]; row++) {
            tau2_AO->matrix[Gpr][row][pr] += value * tau1_AO->matrix[Gpr][row][qs];
            if (anti) tau2_AO->matrix[Gpr][row][pr] -= value * tau1_AO->matrix[Gpr][row][sq];
        }

        /* (pq|sr) */
        Gps = Gp ^ Gs;
        ps = tau1_AO->params->colidx[p][s];
        qr = tau1_AO->params->colidx[q][r];
        rq = tau1_AO->params->colidx[r][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gps]; row++) {
            tau2_AO->matrix[Gps][row][ps] += value * tau1_AO->matrix[Gps][row][qr];
            if (anti) tau2_AO->matrix[Gps][row][ps] -= value * tau1_AO->matrix[Gps][row][rq];
        }

        if (pq != rs) {
            /* (rs|pq) */
            Grp = Gp ^ Gr;
            rp = tau1_AO->params->colidx[r][p];
            sq = tau1_AO->params->colidx[s][q];
            qs = tau1_AO->params->colidx[q][s];

            for (row = 0; row < tau1_AO->params->rowtot[Grp]; row++) {
                tau2_AO->matrix[Grp][row][rp] += value * tau1_AO->matrix[Grp][row][sq];
                if (anti) tau2_AO->matrix[Grp][row][rp] -= value * tau1_AO->matrix[Grp][row][qs];
            }

            /* (sr|pq) */
            Gsp = Gp ^ Gs;
            sp = tau1_AO->params->colidx[s][p];
            qr = tau1_AO->params->colidx[q][r];
            rq = tau1_AO->params->colidx[r][q];

            for (row = 0; row < tau1_AO->params->rowtot[Gsp]; row++) {
                tau2_AO->matrix[Gsp][row][sp] += value * tau1_AO->matrix[Gsp][row][rq];
                if (anti) tau2_AO->matrix[Gsp][row][sp] -= value * tau1_AO->matrix[Gsp][row][qr];
            }
        }

    }

    else if (p == q && r == s) {
        /* (pq|rs) */
        Gpr = Gp ^ Gr;
        pr = tau1_AO->params->colidx[p][r];
        qs = tau1_AO->params->colidx[q][s];
        sq = tau1_AO->params->colidx[s][q];

        for (row = 0; row < tau1_AO->params->rowtot[Gpr]; row++) {
            tau2_AO->matrix[Gpr][row][pr] += value * tau1_AO->matrix[Gpr][row][qs];
            if (anti) tau2_AO->matrix[Gpr][row][pr] -= value * tau1_AO->matrix[Gpr][row][sq];
        }

        if (pq != rs) {
            /* (rs|pq) */
            Grp = Gp ^ Gr;
            rp = tau1_AO->params->colidx[r][p];
            sq = tau1_AO->params->colidx[s][q];
            qs = tau1_AO->params->colidx[q][s];

            for (row = 0; row < tau1_AO->params->rowtot[Grp]; row++) {
                tau2_AO->matrix[Grp][row][rp] += value * tau1_AO->matrix[Grp][row][sq];
                if (anti) tau2_AO->matrix[Grp][row][rp] -= value * tau1_AO->matrix[Grp][row][qs];
            }
        }
    }
    return;
}

}  // namespace cclambda
}  // namespace psi
